APNICから直接割当。
9月23日のメールで通知が来ていたが、すっかり見落としていた(^^;
それにしてもIETF76 広島の為だけに/32を割り当てるなんて、
なんて、豪勢で素敵なのでしょう? :D

> apnic	JP	ipv6	2001:dfb::	32	20090916	assigned

inet6num:     2001:0DFB::/32
netname:      IETF76-JP
descr:        IETF76 Local Host Committee
descr:        for the 76th IETF meeting in Hiroshima, Japan
descr:        from Nov 8 through Nov 13, 2009
remarks:      This prefix is used since Oct 1st through Nov 23rd, 2009
country:      JP
admin-c:      JM46-AP
tech-c:       AK27-AP
status:       ASSIGNED PORTABLE
mnt-by:       APNIC-HM
mnt-lower:    MAINT-JP-WIDE
notify:       ietf-noc@wide.ad.jp
remarks:      -+-+-+-+-+-+-+-+-+-+-+-++-+-+-+-+-+-+-+-+-+-+-+-+-+-+
remarks:      This object can only be updated by APNIC hostmasters.
remarks:      To update this object, please contact APNIC
remarks:      hostmasters and include your organisation's account
remarks:      name in the subject line.
remarks:      -+-+-+-+-+-+-+-+-+-+-+-++-+-+-+-+-+-+-+-+-+-+-+-+-+-+
changed:      hm-changed@apnic.net 20090916
source:       APNIC